Curable resin systems have been modified with fillers so as to render them thixotropic so that they can be trowelled. Such fillers as asbestos and colloidal silica have been used. These fillers are very dusty which provides an unsuitable environment when mixing into the resin systems. Furthermore, asbestos is believed to possess carcinogenic tendencies.
It has now been discovered that the dustiness of these fillers can be reduced by employing a mixture of amorphous pyrogenic or fumed silica with a micro or short fiber inorganic material. Such mixtures are advantageous in that they are free-flowing, relatively dust free and are more readily mixed into the resin system than the filler without the micro or short fiber inorganic filler material. Another advantage to the filler mixture is that less quantities of the micro or short fiber inorganic filler material are required to render the resin system trowelable when it is employed with the amorphous-pyrogenic or fumed silica.